1. Field
One or more example embodiments relate to technology to reduce an electromagnetic wave in a wireless power transmission device, and more particularly, to an apparatus and method for reducing an electromagnetic wave that influences a wireless power transmission device or is externally emitted, except for power transmitted in a process of transmitting wireless power or energy.
2. Description of Related Art
Wireless power transmission technology was mainly used in the field of smart phones. Recently, the technology is spreading to the field of wearable devices, Internet of Things (IoT), or electric vehicle charging. As power to be transmitted increases from few watts (W) of low-output power to few kilowatts (kW) of high-output power, there is growing concern about emission of electromagnetic waves not intended to be transmitted.
To transmit wireless power, a transmission circuit that generates high-output and high-frequency power, a coil to transfer the power, and a reception circuit are needed. In general, the transmission circuit uses square waves, and thus harmonics except for power transmission frequencies may be transmitted or radiated through a conductive wire, or emitted externally directly through the coil. Such harmonics may cause malfunction of components in the circuit or interfere with other devices near a wireless power transmission device, and thus need to be reduced. Further, devices sensitive to electromagnetic waves have strict limits on electromagnetic wave intensity with respect to power signals except for power transmission frequencies. To use the wireless power transmission device in conjunction with such devices, development of a product that satisfies the limits on electromagnetic wave intensity is needed.